Back draft valve for blast furnace installation



April 22, 1969 D. H. REGELIN ETAL 3,439,910

BACK DRAFT VALVE FOR BLAST FURNACE INSTALLATION Filed July 27, 1966 Sheet of 3 FI6.5A a mass FIGJ - INVENTORS Dana/d fieyelz'lr BY kiwi Zfiye/s p 1969 D. H. REGELIN ETAL 3,439,910

BACK DRAFT VALVE FOR BLAST FURNACE INSTALLATION Sheet Filed July 27, 1966 5 Sn 7 1 E s m mxd a %a v2 T W fi T HIM/WA W M fl w m April 1969 D. H. REGELIN ETAL 3,439,910

BACK DRAFT VALVE FOR BLAST FURNACE INSTALLATION Filed July 27, 1966 Sheet 3 of 5 INVENTORS Dana/a Faye/[n BY Jalmfi [rye/s gm M M Q mu,

ATTORNEYS United States Patent 3,439,910 BACK DRAFT VALVE FOR BLAST FURNACE INSTALLATION Donald H. Regelin, Bridgeville, and Jakob Engels, Pittsburgh, Pa., assignors to Zimmermann & Jansen G.m.b.H., Duren, Rhineland, Germany, a corporation of Germany Filed July 27, 1966, Ser. No. 568,193 Int. Cl. F276 7/00; C21b 9/12 US. Cl. 26629 10 Claims ABSTRACT OF THE DISCLOSURE A back drafting valve assembly in which the valve element and its seat are normally retained in fixed position by an annular element. The annular element is defined by a split ring which is separable so that the valve element and seat are movable to an easily accessible location for maintenance and repair purposes.

The present invention relates to a back draft valve arrangement for use in connection with a blast furnace installation.

A blast furnace installation of the type involved herein is one in which a plurality of hot blast stoves are adapted to supply a continuous stream of hot blast to a blast furnace. This is accomplished by sequentially heating up the stoves during the On Gas cycle and thereafter passing a stream of cold air therethrough during the On Blast cycle so that said heated stream defines the hot blast to be supplied to the blast furnace. The complete operation of a multi-stove blast furnace installation as contemplated herein is fully described in US Patents Nos. 2,931,635

and 3,034,775, both of which are assigned to the assignee hereof.

When, in an installation as contemplated herein, it is necessary to make repairs in the furnace itself, it is obviously imperative to remove from the furnace all gases which could be harmful and cause explosions if improperly admixed with air.

Taking the blast off the blast furnace still leaves some residual pressure within the furnace which may be developed by chemical reactions which proceed for a considerable period of time even without the presence of air. This residual pressure is normally relieved by establishing a continuous passage for the residual gases from the furnace through the hot blast stoves and through the stack normally associated with the stoves where these residual gases escape into the atmosphere in a harmless manner. The practice of removing these residual gases in this manner is commonly referred to as back drafting, in view of the fact that the stove stack induces a natural draft.

Another type of back draft system, and the one which is the subject of the present invention, is a system wherein a separate stack, much smaller than the stack used on the stoves, is provided between the furnace and the nearest of the stoves. This separate stack is used only for the back drafting operation so that when the stoves are not in back drafting operation, the separate stack is closed by a valve commonly known as a back draft valve. In the conventional arrangement for this type of back drafting operation, wherein a separate stack is used for back drafting, the back draft valve is located at the top of the separate stack and is normally of the flap type. During the normal operation of the stoves, when the back drafting valve is closed, a substantial amount of pressure is applied to the flap type back drafting valve necessitating means for counteracting this pressure at the opposite side of the flap type valve. A fiap valve of the type referred to hereabove is described in Patent No. 2,879,799, assigned to the assignee hereof.

Patented Apr. 22, 1969 The above arrangement has been found to be less than satisfactory for two principal reasons. The first reason is due to the above mentioned need of providing means for applying substantial pressure at the outer side of the flap valve, during the normal operation of the installation, to counteract the substantial pressure on the inner side of the flap valve. The other principal reason is that the conventional flap type back drafting valve is located at an elevation considerably higher than the normal operating platforms, frequently located at an elevation approximating the elevation of the top or bleeder elevation of the blast furnace and is therefore not easily or conveniently accessible for routine maintenance thereof and for making necessary repairs thereon.

In accordance with the present invention, there has been provided a back drafting valve which overcomes the two aforementioned basic difliculties. More specifically, in accordance with the invention, the back drafting valve is a mushroom type valve arranged in such a way that during the normal operation of the stove, the air pressures on the inner side of the valve have a tendency to force the mushroom against its seat for securely maintaining the latter in firmly closed position. This arrangement obviates the need for providing equalizing pressure on the opposite or outer side of the valve to maintain the latter in its closing position. Further, in accordance with the invention, the back drafting valve is located only slightly above the hot blast main of the furnace, at a considerably lower elevation than the flap type valve, so that access thereto is rendered far more convenient, for maintenance and repair purposes, than is the case with the flap type back drafting valve located at the top of the stack. Further, in accordance with the invention the back drafting valve is provided with a split ring arrangement which maintains the mushroom and seat therefor in its requisite positions, during the operation of the system, but which split ring can be removed in order to allow the mushroom and the seat to be easily retracted for the purpose of maintenance and repair.

It is therefore an object of the present invention to provide a back drafting valve which is easily accessible for maintenance and repair purposes.

Another object is the provision of a back drafting valve in which the pressure of the air during the normal operation of the installation has a tendency to force the valve member against its seat.

Another object is the provision of a mushroom valve maintained in position during the normal operation by a ring, which ring is split and is removable to permit convenient retraction of the valve and seat therefor for maintenance and repair purposes.

The above and other objects, features and advantages of the present invention will be more fully understood from the following description considered in connection with the accompanying drawings.

In the drawings:

FIG. 1 is a front elevation view of the back draft valve in accordance with the invention, and of the pipes connected thereto with parts broken away;

FIG. 2 is a longitudinal cross sectional view of the valve, on an enlarged scale, with parts broken away, showing the valve in the open position, with the mushroom element in section;

FIG. 3 is a view similar to FIG. 2 showing the valve in closed position;

FIG. 4 is an elevational view, partly in section, of the valve arrangement after the split ring has been removed and the mushroom element and seat therefor have been partially retracted; and

FIG. 5A and FIG. 5B are perspective views, respectively, of the two split rings sections, when removed from the valve assembly.

Referring now to the drawings and particularly FIG. 1, there is shown a pipe 10 which could be the bustle pipe of the furnace or the hot blast main for the stoves. Pipe 10 is suitably supported by means of posts 12, slightly above ground level or stove operating platform G. A relatively short pipe length 14 is in fluid communication with pipe 10 and the upper end of pipe length 14 is connected to back drafting valve 16 in accordance with the invention. Valve 16 is in fluid communication at the other side thereof with a pair of symmetrically arranged conduits 18 which in turn merge into pipe 20, the latter defining the aforementioned separate stack of substantial height, the outer end of which defines an aperture into the atmosphere. Valve 16 is provided with means located in housing 22 for operating the valve, such means including opening and closing mechanisms for the valve and cooling means therefor, all as more fully described hereafter. Valve 16, Whether in fluid communication with the bustle pipe or the hot blast main, is always located between the furnace and the hot blast stoves. It is undestood that these several conduits and pipe sections are suitably supported by conventional support means not shown.

Referring now to FIG. 2 and FIG. 3, valve 16 is a mushroom type valve comprising mushroom element 24 which is substantially hollow so that it can be cooled by a circulating coolant entering the valve element through inlet 26 and exiting the same through outlet 28, the path of the circulating coolant being indicated by arrows 30. The coolant and means for circulating the same are provided in a conventional way in housing 22.

Housing 22 carries thereabove mechanism such as motor 32 or equivalent for lowering and raising mushroom element 24 in order, respectively, to open and close valve 16. When valve 16 is closed, as shown in FIG. 3, mushroom element 24 is firmly seated against seating ring 34 and for such purpose seating ring 34 and valve member 24 are provided with complementary beveled engaging surfaces 36 and 38. Seating ring 34 is hollow so that it too can be cooled by a circulating coolant entering the seating ring through inlet 40 and exiting the same through outlet 42. A split ring 44 is in sealing relation at its under side with seating ring 34 and at its upper side with short pipe section 46. Short pipe section 46 is provided with an expansion joint 48 and such pipe section leads into pipe sections 18 by means of intermediate symmetrically arranged angular pipe sections 50. Seating ring 34 is supported in sealing relation by valve housing 52. Split ring 44 is made of two half sections 54 and 56 best seen in the perspective views of FIGS. A and 5B, respectively. Each of these half sections is of generally semicircular configuration terminating in apertured mounting plates 58 on split ring section 54 and apertured mounting plates 60 on split ring section 56. When split ring 44 is fully assembled, as shown in FIGS. 1, 2 and 3, confronting mounting plates 58 and 60 are secured to each other by conventional means. Preferably, each split ring section is hollow so that it can be cooled by circulating a coolant therein, for which purpose water inlet and outlets 62 and 64 are provided, respectively, on sections 54 and 56.

From the above, and particularly with reference to FIG. 3, it will be noted that when the back draft valve is closed, during the normal operation of the stoves and blast furnace, the pressure of the air inwardly of the system acts in the general direction of arrows 66 and has the effect of forcing mushroom element 24 against its seating ring 34 to assist and retain the valve in air tight closed position, as required. Thus, when the back draft valve is intended to be closed to prevent escape of the inside air, the pressure of this air works with instead of against the tendency to retain the valve in closed condition. This is in contrast with the flap type valve in which the pressure of the air intended to be retained has a tendency to open the valve, thus requiring auxiliary 4 pressure means on the opposite side of the valve to prevent such opening.

When the back drafting operation is intended for the aforementioned back drafting purposes, it is a very simple matter to lower the mushroom element 24, in the manner shown in FIG. 2, by the conventional mechanisms provided in housing 22. The opening of back draft valve 16, by lowering mushroom element 24 as shown in FIG. 2, permits the aforementioned residual gases to escape via pipe sections 50 and 18 and stack 20 into the atmosphere. It will be understood, however, that before the back drafting operation is commenced, the back draft valve 16 is isolated from the stoves by means of suitable valve means usually located in the hot blast main.

In accordance with one of the principal features of the invention, the back draft valve is easily accessible for maintenance and repair purposes, as best illustrated in FIG. 4. More specifically, access to the back draft valve is obtained by removing split ring 44 and such is done without difficulty by disconnecting and completely removing the two split ring sections 54 and 56. In connection with the removal of half sections 54 and 56, it will be noted, especially from FIGS. 2 and 3, that these half sections are provided with stepped down portions 68 and 70 which match with complementary sections 72 and 74, respectively (see FIG. 4) on seating ring 34 and the lower end of pipe section 46, for the purpose of defining means for positioning and locating the half sections when they are reassembled in the valve assembly.

Following removal of the split ring 44, the upper part of housing 22, namely, mushroom element carrying part 76 is detached from the remainder of the housing by disconnecting peripheral flanges 78 and 80 from each other, after which said part 76 is raised. As best seen in FIG. 4, the raising of part 76 results in the lifting of mushroom element 24, as well as seating ring 34 carried thereby. As is evident from FIG. 4, the removal of split ring 44 removes all obstacles to the raising of mushroom element 24 above flange 78, to the extent that it may be necessary for clear access to the mushroom element 24, as well as access inside of the valve 16. In this connection, it will be noted that the maximum outside diameter of seating ring 34 is less than the inside diameter of any pipe sections located thereabove. In order to facilitate the raising of mushroom element carrying member 76 as well as the portion of housing 22 thereabove which includes motor 32, there may be provided at the lower end of stack 20 means 82, such as pully or equivalent means, for use in cooperation with power driven lifting means.

Thus, it is seen that back draft valve 16, primarily because it is provided with a removable split ring against which the valve seating ring bears, enables the mushroom element of the valve to be easily withdrawn to where it is easily accessible for maintenance and repair. Further, the withdrawal of the mushroom element permits easy access interiorly of the valve housing, also for the purpose of maintenance and repair. The location of the back draft valve 16, as best seen in FIG. 1, highlights the convenience afforded by the present invention, as all parts are easily accessible slightly above ground or operating platform level.

From the foregoing, it is evidently clear that the present invention accomplishes all of the objects of the invention, namely, the provision of a back drafting valve which is easily and totally accessible for maintenance and repair, and one which is so constructed that when the back draft valve is intended to be closed, the inner air pressure aids in retaining the valve in closed position.

While we have herein shown and described the preferred embodiment of our invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that in the illustrated embodiment certain changes in the details of construction and in the form and arrangement of parts may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.

Having thus described our invention, what we claim and desire to secure by Letters Patent is:

1. In a blast furnace installation in which a plurality of hot blast stoves are adapted to supply hot blast to a blast furnace by means of an interconnecting conduit, a valve assembly fluidly interconnected at one end thereof, with said conduit comprising:

a valve closure element;

seating means for said closure element;

said closure element being movable in a given direction from a closing position thereof in which it is in airtight relation with said seating means at one side thereof to an open position in which it is spaced from said seating means;

an annular element normally positioned in engagement with said seating means at the opposite side thereof for opposing movement of said seating means in a direction opposite to said given direction;

said annular element being made of a plurality of detachably interconnected nonannular sections separable from each other, from said valve closure element, and from said seating means;

whereby said seating means and valve closure element are movable in said opposite direction to a position in which they are accessible for maintenance and repair when said sections are detached and said ring is removed from said normal position.

2. A valve assembly in accordance with claim 1, wherein the opposite end of said valve assembly is in fluid communication with conduit means leading to the atmosphere.

3. A valve assembly in accordance with claim 2, wherein said given direction of movement for said closure element is toward said one end of the valve assembly.

4. A valve assembly in accordance with claim 3,

wherein said valve is normally closed during the operation 4 of the blast furnace and the pressure of the air required during said operation acts upon said closure element in a direction opposite to said given direction for retaining said element in closed position against seating means.

5. A valve assembly in accordance with claim 1, wherein said closure element is a mushroom shaped member and said seating means is ring shaped, both of which are hollow for circulating cooling means therethrough.

6. A valve assembly in accordance with claim 5, wherein said annular element comprises two detachably interconnected half circular sections, each of which is hollow for circulating a coolant therethrough.

7. A valve assembly in accordance with claim 2, wherein there is provided a stove operating platform which defines means for supporting said valve assembly and wherein said valve assembly is located slightly higher than said stove operating platform level.

8. A valve assembly in accordance with claim 2, wherein said conduit means leading to the atmosphere comprise a pair of pipes emanating from said opposite end in diverging relation and merging into one pipe a substantial distance from said opposite end.

9. A valve assembly in accordance with claim 4, wherein said conduit means leading to the atmosphere comprise a pair of pipes emanating from said opposite end in diverging relation and merging into one pipe a substantial distance from said opposite end.

10. A valve assembly in accordance with claim 4, wherein said closure element is a mushroom shaped member, said seating means is ring shaped and said annular element comprises two detachably interconnected sections.

References Cited UNITED STATES PATENTS 860,062 7/1907 Rust 137-4542 X 860,865 7/1907 Hartman 251360 X 1,027,781 5/ 1912 Sweetser 26630 2,204,724 6/1940 Cope 137340 2,671,765 3/1954 McGrath et a1 Z6616 X 3,159,385 12/1964 Flanagan 263-19 0 J. SPENCER OVERHOLSER, Primary Examiner.

J. S BROWN, Assistant Examiner. 

